public void DivideByTest()
{
var num1 = new Rational {
Numerator = 2, Denominator = 3
};
var num2 = new Rational {
Numerator = 5, Denominator = 6
};
var result = num1.DivideBy(num2);
Assert.AreEqual(4, result.Numerator);
Assert.AreEqual(5, result.Denominator);
}